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Cetraria nigricans Nyl.
Family: Parmeliaceae
Cetraria nigricans image
Stephen Sharnoff  
Thompson, J., 1984. American Arctic Lichens: The Macrolichens.
Thallus foliose, forming tufts and small mats on the substrate, the lobes narrow, to 1 mm broad, slightly channeled, the margins with cilia which may be simple or branched; upper side dark brown or olive-brown; lower side pale brown to tan, with sparse short and inconspicuous pseudocyphellae. Apothecia but no spores were present in North America in specimens from Franklin Mts., McConnell Range, N.W.T. Bird 27188. In Scandinavian material apothecia were to 3 mm broad, the margins spinulose, the disk convex, reddish-brown, shining; hypothecium hyaline; hymenium with the upper part yellowish brown, 65-75 μ; spores 8, simple, hyaline, ellipsoid, 9-10 x 4-5 μ.

Reactions: medulla K—, C—, KC—, P—, 1+ blue.

Contents: protolichesterinic and rangi-formic acids.

This species grows on rocks and soil. It is circumpolar and low arctic, ranging in North America from Labrador and Newfoundland to Alaska. Its southern areas are in the alpine or in very exposed sites.